Copper electrodeposition in microelectronics

ABSTRACT

A method and composition for electroplating Cu onto a substrate in the manufacture of a microelectronic device involving and electrolytic solution containing a source of Cu ions and a substituted pyridyl polymer compound for leveling.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit from U.S. application Ser. No.60/531,771, filed Dec. 22, 2003 and is a continuation-in-part of U.S.Ser. No. 10/091,106, filed Mar. 5, 2002, now U.S. Pat. No. 7,316,772.

BACKGROUND OF THE INVENTION

This invention relates to a method, compositions, and additives forelectrolytic Cu metallization in the field of microelectronicsmanufacture.

Electrolytic Cu metallization is employed in the field ofmicroelectronics manufacture to provide electrical interconnection in awide variety of applications, such as, for example, in the manufactureof semiconductor integrated circuit (IC) devices. The demand formanufacturing semiconductor IC devices such as computer chips with highcircuit speed and high packing density requires the downward scaling offeature sizes in ultra-large-scale integration (ULSI) andvery-large-scale integration (VLSI) structures. The trend to smallerdevice sizes and increased circuit density requires decreasing thedimensions of interconnect features. An interconnect feature is afeature such as a via or trench formed in a dielectric substrate whichis then filled with metal to yield an electrically conductiveinterconnect. Further decreases in interconnect size present challengesin metal filling.

Copper has been introduced to replace aluminum to form the connectionlines and interconnects in semiconductor substrates. Copper has a lowerresistivity than aluminum and the thickness of a Cu line for the sameresistance can be thinner than that of an aluminum line. Copper can bedeposited on substrates by plating (such as electroless andelectrolytic), sputtering, plasma vapor deposition (PVD), and chemicalvapor deposition (CVD). It is generally recognized electrochemicaldeposition is the best method to apply Cu since it can provide highdeposition rates and offer low cost of ownership.

Copper plating methods must meet the stringent requirements of thesemiconductor industry. For example, Cu deposits must be uniform andcapable of flawlessly filling the small interconnect features of thedevice, for example, with openings of 100 nm or smaller.

Electrolytic Cu systems have been developed which rely on so-called“superfilling” or “bottom-up growth” to deposit Cu into high aspectratio features. Superfilling involves filling a feature from the bottomup, rather than at an equal rate on all its surfaces, to avoid seams andpinching off that can result in voiding. Systems consisting of asuppressor and an accelerator as additives have been developed forsuperfilling. As the result of momentum of bottom-up growth, the Cudeposit is thicker on the areas of interconnect features than on thefield area that does not have features. These overgrowth regions arecommonly called overplating, mounding, bumps, or humps. Smaller featuresgenerate higher overplating humps due to faster superfill speed. Theoverplating poses challenges for later chemical and mechanical polishingprocesses that planarize the Cu surface.

To control overplating, a third additive component called leveler isintroduced to create surface “leveling,” i.e., to reduce the momentum ofbottom-up growth created by accelerator and suppressor. Although aleveler creates a more planar Cu surface, it is commonly recognized thatleveler can have negative impact on the bottom-up growth, especially athigh leveler concentration that can slow the superfilling growth rate. Acommon practice is to use leveler within a tight concentration windowthat strikes a compromise between the overplating and superfillingperformances.

As chip architecture gets smaller, with interconnects having openings onthe order of 100 nm and smaller through which Cu must grow to fill theinterconnects, there is a need for enhanced bottom-up speed. That is,the Cu must fill “faster” in the sense that the rate of growth in thevertical direction must be substantially greater (e.g., 50%, 75%, ormore) than the rate of growth in the horizontal direction, and even moreso than in conventional superfilling of larger interconnects. However,the extraordinary speed of bottom-up growth on these fine structuresgenerates significantly large dimension of overplating humps thatrequire more leveler to level. But to further increase levelerconcentration reduces superfilling speed that is especially critical forthese fine interconnect structures.

In addition to superfilling and overplating issues, micro-defects mayform when electrodepositing Cu for filling interconnect features. Onedefect that can occur is the formation of internal voids inside thefeatures. As Cu is deposited on the feature side walls and top entry ofthe feature, deposition on the side walls and entrance to the featurecan pinch off and thereby close access to the depths of the featureespecially with features which are small (e.g., <100 nm) and/or whichhave a high aspect ratio (depth:width). An internal void can form in thefeature if Cu solution flow into the feature is closed off during theelectrolytic process. An internal void can interfere with electricalconnectivity through the feature.

Microvoids are another type of defect which can form during or afterelectrolytic Cu deposition due to uneven Cu growth or grainrecrystallization that happens after Cu plating.

In a different aspect, some local areas of a semiconductor substrate,typically areas where there is a Cu seed layer deposited by physicalvapor deposition, may not grow Cu during the electrolytic deposition,resulting in pits or missing metal defects. These Cu voids areconsidered to be “killer defects,” as they reduce the yield ofsemiconductor manufacturing. Multiple mechanisms contribute to theformation of these Cu voids, including the semiconductor substrateitself. However, Cu electroplating chemistry has influence on theoccurrence and population of these defects.

Other defects are surface protrusions, which are isolated depositionpeaks occurring at localized high current density sites, localizedimpurity sites, or otherwise. Copper plating chemistry has influence onthe occurrence of such protrusion defects. Although not considered asdefects, Cu surface roughness is also important for semiconductor wafermanufacturing. Generally, a bright Cu surface is desired as it canreduce the swirl patterns formed during wafer entry in the platingsolution. Roughness of Cu deposits makes it more difficult to detectdefects by inspection, as defects may be concealed by peaks and valleysof rough surface topography. Moreover, smooth growth of Cu is becomingmore important for flawlessly filling of fine interconnect structures asthe roughness can cause pinch off of feature and thereby close access tothe depths of the feature. It is generally recognized that Cu platingchemistry has great influence on the roughness of Cu deposits, throughcombined effects of additive components, especially leveler. From thisperspective, judicious use of leveler can result in better superfillingperformance.

SUMMARY OF THE INVENTION

Briefly, therefore, the invention is directed to a method forelectroplating Cu onto a substrate in the manufacture of amicroelectronic device comprising immersing the substrate in anelectrolytic solution containing Cu in an amount sufficient toelectrodeposit Cu onto the substrate and a leveling agent comprising asubstituted pyridyl polymer compound, and supplying electrical currentto the electrolytic solution to deposit Cu onto the substrate.

In another aspect the invention is directed to a composition forelectroplating Cu onto a substrate in the manufacture of amicroelectronic device, the composition comprising a source of Cu ionsand a leveling agent comprising a substituted pyridyl polymer compound.

Other objects and features of the invention will be in part apparent andin part pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an SEM image of a cross-section of a wafer plated according tothe method described in Example 24.

FIG. 2 is an SEM image of a cross-section of a wafer plated according tothe method described in Example 24.

FIG. 3 is an SEM image of a cross-section of a wafer plated according tothe method described in Example 24.

FIG. 4 is an SEM image of a cross-section of a wafer plated according tothe method described in Example 24.

FIG. 5 is an SEM image of a cross-section of the center portion of awafer plated according to the method described in Example 25.

FIG. 6 is an SEM image of a cross-section of the edge portion of a waferplated according to the method described in Example 25.

FIG. 7 is an SEM image of a cross-section of the center portion of awafer plated according to the method described in Example 25.

FIG. 8 is an SEM image of a cross-section of the edge portion of a waferplated according to the method described in Example 25.

FIG. 9 is an SEM image of a cross-section of the center portion of awafer plated according to the method described in Example 25.

FIG. 10 is an SEM image of a cross-section of the edge portion of awafer plated according to the method described in Example 25.

FIG. 11 is an SEM image of a cross-section of the center portion of awafer plated according to the method described in Example 26.

FIG. 12 is an SEM image of a cross-section of the edge portion of awafer plated according to the method described in Example 26.

FIG. 13 is an SEM image of a cross-section of the center portion of awafer plated according to the method described in Example 26.

FIG. 14 is an SEM image of a cross-section of the edge portion of awafer plated according to the method described in Example 26.

FIG. 15 is an SEM image of a cross-section of the center portion of awafer plated according to the method described in Example 26.

FIG. 16 is an SEM image of a cross-section of the edge portion of awafer plated according to the method described in Example 26.

FIG. 17 is an SEM image of a cross-section of the center portion of awafer plated according to the method described in Example 27.

FIG. 18 is an SEM image of a cross-section of the edge portion of awafer plated according to the method described in Example 27.

FIG. 19 is an SEM image of a cross-section of the center portion of awafer plated according to the method described in Example 27.

FIG. 20 is an SEM image of a cross-section of the edge portion of awafer plated according to the method described in Example 27.

FIG. 21 is an SEM image of a cross-section of the center portion of awafer plated according to the method described in Example 27.

FIG. 22 is an SEM image of a cross-section of the edge portion of awafer plated according to the method described in Example 27.

DETAILED DESCRIPTION

In accordance with this invention, an additive based on substitutedpyridyl compounds is incorporated into an electroplating bath for Cuplating in the manufacture of microelectronics. In one embodiment, theelectroplating bath is for use in depositing Cu onto a semiconductor ICdevice substrate such as a silicon wafer, including Cu filling ofinterconnect features.

A significant advantage of the additive of the invention is an enhancedleveling effect without substantially interfering with superfilling ofCu into high aspect ratio features. That is, because the leveler of theinvention does not substantially interfere with superfilling, the Cubath can be formulated with a combination of accelerator and suppressoradditives which provides a rate of growth in the vertical directionwhich is substantially greater than the rate of growth in the horizontaldirection, and even more so than in conventional superfilling of largerinterconnects. The compositions of the invention address the increase inrisk of mounding which typically occurs as the rate of superfilling isincreased. The additive also appears to have advantages in terms ofreducing defects, increasing brightness, minimizing overplating,improving uniformity, and reducing underplating in some large features.

The leveler of the invention is a substituted pyridyl compound selectedfrom among those which are soluble in a Cu plating bath, retain theirfunctionality under electrolytic conditions, do not yield deleteriousby-products under electrolytic conditions (at least neither immediatelynor shortly thereafter), and yield the desired leveling effect. In onesuch embodiment the leveler is a pyridinium compound and, in particular,a quaternized pyridinium salt. A pyridinium compound is a compoundderived from pyridine in which the nitrogen atom of the pyridine isprotonated. A quaternized pyridinium salt is distinct from pyridine, andquaternized pyridinium salt-based polymers are distinct frompyridine-based polymers, in that the nitrogen atom of the pyridine ringis quaternized in the quaternized pyridinium salt and quaternizedpyridinium salt-based polymers. The levelers of the invention includederivatives of a vinyl pyridine, such as derivatives of 2-vinyl pyridineand, in certain preferred embodiments, derivatives of 4-vinyl pyridine.The leveler compound polymers of the invention encompass homo-polymersof vinyl pyridine, co-polymers of vinyl pyridine, quaternized salts ofvinyl pyridine, and quaternized salts of these homo-polymers andco-polymers. Some specific examples of such compounds include, forexample, poly(4-vinyl pyridine), the reaction product of poly(4-vinylpyridine) with dimethyl sulfate, the reaction product of 4-vinylpyridine with 2-chloroethanol, the reaction product of 4-vinyl pyridinewith benzylchloride, the reaction product of 4-vinyl pyridine with allylchloride, the reaction product of 4-vinyl pyridine with4-chloromethylpyridine, the reaction product of 4-vinyl pyridine with1,3-propane sultone, the reaction product of 4-vinyl pyridine withmethyl tosylate, the reaction product of 4-vinyl pyridine withchloroacetone, the reaction product of 4-vinyl pyridine with2-methoxyethoxymethylchloride, the reaction product of 4-vinyl pyridinewith 2-chloroethylether, the reaction product of 2-vinyl pyridine withmethyl tosylate, the reaction product of 2-vinyl pyridine with dimethylsulfate, the reaction product of vinyl pyridine and a water solubleinitiator, poly(2-methyl-5-vinyl pyridine), and1-methyl-4-vinylpyridinium trifluoromethyl sulfonate, among others. Anexample of a co-polymer is vinyl pyridine co-polymerized with vinylimidazole.

The molecular weight of the substituted pyridyl polymer compoundadditives of the invention in one embodiment is on the order of about160,000 g/mol or less. While some higher molecular-weight compounds aredifficult to dissolve into the electroplating bath or to maintain insolution, other higher molecular weight compounds are soluble due to theadded solubilizing ability of the quaternary nitrogen cation. Theconcept of solubility in this context is reference to relativesolubility, such as, for example, greater than 60% soluble, or someother minimum solubility that is effective under the circumstances. Itis not a reference to absolute solubility. The foregoing preference of160,000 g/mol or less in certain embodiments is not narrowly critical.The substituted pyridyl polymers selected are soluble in a Cu platingbath, retain their functionality under electrolytic conditions, and donot yield deleterious by-products under electrolytic conditions, atleast neither immediately nor shortly thereafter.

Homo polymers of poly(4-vinyl pyridine) are available commercially. Apoly(4-vinyl pyridine) with an average molecular weight of from 10,000to 20,000 with a mean of 16,000 is available from Reilly Industries,Inc. under the trade designation Reilline 410 Solution SOQ.Additionally, poly(4-vinyl pyridines) with average molecular weights ofabout 60,000 and 160,000 are available from Aldrich Chemical Company.

In those embodiments where the leveler compound is a reaction product ofa vinyl pyridine or poly(vinyl pyridine), it is obtained by causing avinyl pyridine or poly(vinyl pyridine) to react with an alkylating agentselected from among those which yield a product which is soluble, bathcompatible, and effective for leveling. In one embodiment candidates areselected from among reaction products obtained by causing vinyl pyridineor poly(vinyl pyridine) to react with a compound of formula 1:R₁-L  (1)

-   -   wherein R₁ is alkyl, alkenyl, aralkyl, heteroarylalkyl,        substituted alkyl, substituted alkenyl, substituted aralkyl or        substituted heteroarylalkyl; and    -   L is a leaving group.

A leaving group is any group that can be displaced from a carbon atom.In general, weak bases are good leaving groups. Exemplary leaving groupsare halides, methyl sulfate, tosylates, and the like.

In another embodiment, R₁ is alkyl or substituted alkyl; preferably, R₁is substituted or unsubstituted methyl, ethyl, straight, branched orcyclic propyl, butyl, pentyl or hexyl; in one embodiment R₁ is methyl,hydroxyethyl, acetylmethyl, chloroethoxyethyl or methoxyethoxymethyl.

In a further embodiment, R₁ is alkenyl; preferably, R₁ is vinyl,propenyl, straight or branched butenyl, straight, branched or cyclicpentenyl or straight, branched, or cyclic hexenyl; in one embodiment R₁is propenyl.

In yet another embodiment, R₁ is aralkyl or substituted aralkyl;preferably, R₁ is benzyl or substituted benzyl, naphthylalkyl orsubstituted naphthylalkyl; in one

embodiment R₁ is benzyl or naphthylmethyl.

In still another embodiment, R₁ is heteroarylalkyl or substitutedheteroarylalkyl; preferably, R₁ is pyridylalkyl; particularly, R₁ ispyridylmethyl.

In a further embodiment, L is chloride, methyl sulfate (CH₃SO₄ ⁻), octylsulfate (C₈H₁₈SO₄ ⁻), trifluoromethanesulfonate (CF₃SO₃ ⁻),chloroacetate (CH₂ClC(O)O⁻), or tosylate (C₇H₇SO₃ ⁻); preferably, L ismethyl sulfate, chloride or tosylate.

In one such embodiment the leveler compound ispoly(1-methyl-4-vinylpyridinium methyl sulfate) obtained by reactingpoly(4-vinyl pyridine) with dimethyl sulfate as follows:

Water soluble initiators can be used to prepare polymers of vinylpyridine, though they are not used in the currently preferredembodiments or in the working examples. Exemplary water solubleinitiators are peroxides (e.g., hydrogen peroxide, benzoyl peroxide,peroxybenzoic acid, etc.) and the like, and water soluble azo initiatorssuch as 4,4′-Azobis(4-cyanovaleric acid).

In a further embodiment, the leveler constitutes a component of amixture of one of the above-described polymers with a quantity of amonomer which is, for example, a monomeric vinyl pyridine derivativecompound. In one such embodiment, the mixture is obtained byquaternizing a monomer to yield a quaternized salt which then undergoesspontaneous polymerization. The quaternized salt does not completelypolymerize; rather, it yields a mixture of the monomer and spontaneouslygenerated polymer. In a currently preferred embodiment, 4-vinyl pyridineis quaternized by reaction with dimethyl sulfate, and spontaneouspolymerization occurs according to the following reaction scheme (40-65°C.)

This represents the materials of Example 4 reacted according to Method 3of Example 1 hereinbelow. The monomer fraction is increased with anincrease in amount of

methanol used in the quaternization reaction; that is, the degree ofspontaneous polymerization is decreased. While the resulting levelersystem is a mixture of the polymer and the monomer, it preliminarilyappears that only the polymer actively performs leveling function.

The active ingredient of the substituted pyridyl polymer compounds areincorporated into the electroplating bath at concentrations of about0.01 mg/L to about 100 mg/L. In this regard, the active ingredient is ahomo-polymer of vinyl pyridine, a co-polymer of vinyl pyridine, aquaternized salt of vinyl pyridine, and/or a quaternized salt of thesehomo-polymers and co-polymers. The active ingredient does not includethe inactive anion associated with the quaternized salts. In oneembodiment, the active ingredients of the compounds are present in thebath at concentrations of between about 0.1 mg/L (0.4 micromole/L) andabout 25 mg/L (108 micromole/L) or higher.

While the substituted pyridyl polymers of the invention can be used in avariety of electroplating baths, in one embodiment it is preferred touse them in combination with particular suppressors and accelerators asdisclosed in co-assigned U.S. Pat. No. 6,776,893, the entire disclosureof which is expressly incorporated herein by reference. In such asystem, a preferred suppressor is a bath soluble polyether compoundselected from the group consisting of block copolymers ofpolyoxyethylene and polyoxypropylene, a polyoxyethylene orpolyoxypropylene derivative of a polyhydric alcohol and a mixedpolyoxyethylene and polyoxypropylene derivative of a polyhydric alcohol.The polyether suppressor compounds are incorporated typically in aconcentration between about 0.02 and about 2 g/L, more typically betweenabout 0.04 and about 1.5 g/L, and even more typically between about 0.1and 1 g/L. Especially preferred suppressors include polyether compoundsrepresented by Formulae 2, 3 and 4.

wherein x+y+z is 3 to 100, and wherein e+f+g and h+i+j are each 5 to100.

One especially preferred suppressor is apolyoxyethylene/polyoxypropylene block copolymer of ethylenediamine

wherein the molecular weight of the polyoxypropylene (hydrophobe) isabout 2500-3000 and of the polyoxyethylene (hydrophylic unit) is about2500-3000. The molecular weight of the polymer is about 5500. Thispolymer is available from BASF Corporation of Mt. Olive, N.J. under thetrade designation Tetronic® 704.

With regard to accelerators, in a system currently preferred by theapplicants the accelerators are bath soluble organic divalent sulfurcompounds corresponding to the formulaR₁—(S)_(n)RXO₃M  (5)wherein

-   -   M is hydrogen, alkali metal or ammonium as needed to satisfy the        valence;    -   X is S or P;    -   R is an alkylene or cyclic alkylene group of 1 to 8 carbon        atoms, an aromatic hydrocarbon or an aliphatic aromatic        hydrocarbon of 6 to 12 carbon atoms;    -   n is 1 to 6; and    -   R₁ is selected from the group of    -   MO₃XR wherein M, X and R are as defined above,    -   a thiocarbamate represented by the formula

-   -   a xanthate represented by the formula

, andan aminoimine represented by the formula

wherein R₂, R₃, R₄, R₅ and R₆ are independently hydrogen, an alkyl groupof 1 to 4 carbon atoms, a heterocyclic group, or an aromatic group.

Especially preferred accelerators include bath soluble organic divalentsulfur compounds corresponding to Formula 5 above wherein

-   -   R₁ is MO₃XR wherein M, X and R are as defined above or a        thiocarbamate represented by the formula

wherein

-   -   R₂ and R₃ are independently hydrogen, an alkyl group of 1 to 4        carbon atoms, a heterocyclic group or an aromatic group.

An accelerator which is especially preferred is 1-propanesulfonic acid,3,3′-dithiobis, disodium salt according to the following formula:

The accelerator is incorporated typically in a concentration betweenabout 0.5 and about 1000 mg/L, more typically between about 5 and about50 mg/L, and even more typically between about 5 and 30 mg/L.

Optionally, additional leveling compounds of the following types can beincorporated into the bath such as the reaction product of benzylchloride and hydroxyethyl polyethylenimine as disclosed in U.S. PatentPublication No. 20030168343, the entire disclosure of which is expresslyincorporated herein by reference.

While the incorporation of such suppressors, accelerators, and levelingcompounds is not critical to the efficacy of the compounds of thisinvention, at this time the best overall deposit and feature fill isbelieved to be achieved thereby.

One preferred Cu deposition bath comprises a makeup solution, whichcontains about 40 g/L Cu as CuSO₄, about 10 g/L H₂SO₄, and about 50 ppmCl⁻. This preferred overall bath further comprises about 2 ml/L (200ppm) suppressor available from Enthone under the designation ViaForm®suppressor, about 6 ml/L (12 ppm) accelerator available from Enthoneunder the designation ViaForm® accelerator, and about 2.5 ml/L (4 ppm)leveler available from Enthone under the designation ViaForm® leveler.To this bath is also added the substituted pyridyl polymer of thepresent invention.

The substituted pyridyl polymer compound of the invention in theforegoing concentrations and combinations has been discovered to providean enhanced leveling effect without substantially interfering withsuperfilling of Cu into high aspect ratio features. The additive alsoappears to have advantages in terms of reducing defects, increasingbrightness, minimizing overplating, improving uniformity, and reducingunderplating in some large features.

An advantage of the substituted pyridyl polymer additives of theinvention is the reduction in the occurrence of internal voids ascompared to deposits formed from a bath not containing these compounds.Internal voids form from Cu depositing on the feature side walls and topentry of the feature, which causes pinching off and thereby closesaccess to the depths of the feature. This defect is observed especiallywith features which are small (e.g., <100 nm) and/or which have a highaspect ratio (depth:width), for example, >4:1. As access to the featureby Cu is inhibited or closed off, an internal void can be left in thefeature, thereby interfering with electrical connectivity through thefeature. The compounds of the invention appear to reduce the incidenceof internal voids because the compounds interfere less with superfillingthan do other levelers, such that the incidence of closing off of highaspect ratio features is reduced.

As a general proposition, because there is less interference withsuperfilling, leveling can be pursued more aggressively. This is anespecially valuable benefit as chip architecture gets smaller, becausewith interconnect dimensions down at sizes on the order of 100 nm andsmaller, faster superfilling is required in the sense that a muchgreater rate of vertical deposition as compared to a rate of horizontaldeposition is required, and planarity problems and the need for levelingare exacerbated. The present leveler allows one to accelerate thesuperfilling rate by use of accelerator/suppressor combination chemistrywhich would ordinarily result in excessive mounding.

Another advantage of the compositions of the invention is the reductionof Cu voids such as missing metal defects and microvoids. These defectsreduce the yield and reliability of semiconductor IC devices.

Another advantage of the compounds of the invention is the reduction ofgeneral surface roughness on the substrate surface and withininterconnect features. Reducing surface roughness is becomingincreasingly important to achieve flawless fill of fine interconnectstructures as rough Cu growth can potentially pinch off featureentrance, leaving internal voids.

Another advantage of the leveling agents of the invention is thedecrease in the occurrence of surface protrusions, which are isolateddeposition peaks occurring at localized high current density sites,localized impurity, sites, or otherwise. The occurrence of theseprotrusions is reduced as compared to a Cu deposit formed from a baththat does not contain the compounds of the invention.

A further significant advantage of the compounds of the invention is dueto the decrease in dimension of overplating and improved uniformity,which enables deposition of thinner Cu films to achieve planar surfaces,thus less material has to be removed in post-deposition operations. Forexample, chemical mechanical polishing (CMP) is used after electrolyticCu deposition to reveal the underlying features. The more level depositof the invention corresponds to a reduction in the amount of metal whichmust be deposited, therefore resulting in less removal later by CMP.There is a reduction in the amount of scrapped metal and, moresignificantly, a reduction in the time required for the CMP operation.The material removal operation is also less severe which, coupled withthe reduced duration, corresponds to a reduction in the tendency of thematerial removal operation to impart defects. In this regard, for manyof the various embodiments described above, deposition of Cu includesthe deposition of Cu alloys.

The Cu electroplating bath may vary widely depending on the substrate tobe plated and the type of Cu deposit desired. The electrolytic bathsinclude acid baths and alkaline baths. A variety of Cu electroplatingbaths are described in the book entitled Modern Electroplating, editedby F. A. Lowenheim, John Reily & Sons, Inc., 1974, pages 183-203.Exemplary baths include Cu fluoroborate, Cu pyrophosphate, Cu cyanide,Cu phosphonate, and other Cu metal complexes such as methane sulfonicacid. The most typical Cu electroplating bath comprises Cu sulfate in anacid solution.

The concentration of Cu and acid may vary over wide limits; for example,from about 4 to about 70 g/L Cu and from about 2 to about 225 g/L acid.In this regard the compounds of the invention are suitable for use inboth high acid/low Cu systems, and in low acid/high Cu systems. In highacid/low Cu systems, the Cu ion concentration can be on the order of 4g/L to on the order of 3.0 g/L; and the acid concentration may besulfuric acid in an amount of greater than about 50 up to about 225 g/L.In one high acid/low Cu system, the Cu ion concentration is about 17 g/Lwhere the H₂SO₄ concentration is about 180 g/L. In low acid/high Cusystems, the Cu ion concentration can be on the order of greater thanabout 30, 40, and even up to on the order of 55 g/L Cu (greater than 50g/L Cu corresponds to greater than 200 g/L CuSO₄-5H₂O Cu sulfatepentahydrate). The acid concentration in these systems is less than 50,40, and even 30 g/L H₂SO₄, down to about 7 g/L. In one exemplary lowacid/high Cu system, the Cu concentration is about 40 g/L and the H₂SO₄concentration is about 10 g/L.

Chloride ion may also be used in the bath at a level up to 200 mg/L,preferably about 1 to 90 mg/L. The bath also preferably contains anorganic additive system such as accelerator, suppressor, and leveler.

A large variety of additives may typically be used in the bath toprovide desired surface finishes for the Cu plated metal. Usually morethan one additive is used with each additive forming a desired function.The additives are generally used to initiate bottom-up filling ofinterconnect features as well as for improved metal plated appearance(brightness), structure and physical properties such as electricalconductivity. Particular additives (usually organic additives) are usedfor grain refinement, suppression of dendritic growth, and improvedcovering and throwing power. Typical additives used in electroplatingare discussed in a number of references including Modern Electroplating,cited above. A particularly desirable additive system uses a mixture ofaromatic or aliphatic quaternary amines, polysulfide compounds, andpolyethers. Other additives include items such as selenium, tellurium,and sulfur compounds.

Plating equipment for plating semiconductor substrates are well knownand are described in, for example, Haydu et al. U.S. Pat. No. 6,024,856.Plating equipment comprises an electroplating tank which holds Cuelectrolyte and which is made of a suitable material such as plastic orother material inert to the electrolytic plating solution. The tank maybe cylindrical, especially for wafer plating. A cathode is horizontallydisposed at the upper part of tank and may be any type substrate such asa silicon wafer having openings such as trenches and vias. The wafersubstrate is typically coated with a seed layer of Cu or other metal toinitiate plating thereon. A Cu seed layer may be applied by chemicalvapor deposition (CVD), physical vapor deposition (PVD), or the like. Ananode is also preferably circular for wafer plating and is horizontallydisposed at the lower part of tank forming a space between the anode andcathode. The anode is typically a soluble anode.

These bath additives are useful in combination with membrane technologybeing developed by various tool manufacturers. In this system, the anodemay be isolated from the organic bath additives by a membrane. Thepurpose of the separation of the anode and the organic bath additives isto minimize the oxidation of the organic bath additives.

The cathode substrate and anode are electrically connected by wiringand, respectively, to a rectifier (power supply). The cathode substratefor direct or pulse current has a net negative charge so that Cu ions inthe solution are reduced at the cathode substrate forming plated Cumetal on the cathode surface. An oxidation reaction takes place at theanode. The cathode and anode may be horizontally or vertically disposedin the tank.

During operation of the electroplating system, Cu metal is plated on thesurface of a cathode substrate when the rectifier is energized. A pulsecurrent, direct current, reverse periodic current, or other suitablecurrent may be employed. The temperature of the electrolyte may bemaintained using a heater/cooler whereby electrolyte is removed from theholding tank and flows through the heater/cooler and then is recycled tothe holding tank.

It is an optional feature of the process that the plating system becontrolled as described in U.S. Pat. No. 6,024,856 by removing a portionof the electrolyte from the system when a predetermined operatingparameter (condition) is met and new electrolyte is added to the systemeither simultaneously or after the removal in substantially the sameamount. The new electrolyte is preferably a single liquid containing allthe materials needed to maintain the electroplating bath and system. Theaddition/removal system maintains a steady-state constant plating systemhaving enhanced plating effects such as constant plating properties.With this system and method the plating bath reaches a steady statewhere bath components are substantially a steady-state value.

Electrolysis conditions such as electric current concentration, appliedvoltage, electric current density, and electrolyte temperature areessentially the same as those in conventional electrolytic Cu platingmethods. For example, the bath temperature is typically about roomtemperature such as about 20-27° C., but may be at elevated temperaturesup to about 40° C. or higher. The current density is typically up toabout 100 amps per square foot (ASF) typically about 2 to 460 ASF. It ispreferred to use an anode to cathode ratio of about 1:1, but this mayalso vary widely from about 1:4 to 4:1. The process also uses in theelectroplating tank which may be supplied by agitation or preferably bythe circulating flow of recycle electrolyte through the tank. The flowthrough the electroplating tank provides a typical residence time ofelectrolyte in the tank of less than about 1 minute, more typically lessthan 30 seconds, e.g., 10-20 seconds.

The following examples illustrate the invention.

Example 1 Synthetic Methods

Method 1: The pyridine starting material (0.1 mol) listed below wasdissolved in approximately 50 mL of chloroform in a round bottom flask.The reagent (R₁L) (0.105 mol) listed below was added slowly, withstirring, to the starting material solution. After the reagent (R₁L) wasadded, the mixture was heated to reflux until the reaction wasconsidered complete. After heating, the chloroform was removed by rotaryevaporation and the product was worked up by an appropriate methoddepending on its physical and chemical characteristics. The product wasbrought to a final volume in a 100 mL volumetric flask with deionizedwater. A further dilution was performed to bring the active material toa final concentration of 750 mg/L.

Method 2: The pyridine starting material (0.1 mol) was added toapproximately 50 mL of water in a round bottom flask. The reagent (R₁L)(0.105 mol) was added slowly, with stirring, to the starting materialsolution. Depending on the alkylating agent, the initial reaction wasaccompanied by an exotherm. After the reagent (R₁L) was added at 35° C.,the mixture was heated to reflux for one hour. After heating, theproduct was brought to a final volume in a 100 mL volumetric flask withdeionized water. A further dilution was performed to bring the activematerial to a final concentration of 750 mg/L.

Method 3: The pyridine starting material (0.1 mol) was dissolved inapproximately 50 mL of anhydrous methanol in a round bottom flask. Thealkylating agent (0.105 mol) was added slowly, with stirring, to thestarting material solution, while the temperature was no greater than35° C. After the reagent (R₁L) was added, about 2 grams of water wasadded and the mixture was slowly heated to 65-70° C. to hydrolyze anyresidual, e.g., dimethyl sulfate or methyl tosylate. The mixture washeated for several hours until the reaction was considered substantiallycomplete. The methanol was removed by rotary evaporation; but it isacceptable to allow it to remain. The product was brought to a finalvolume in a 100 mL volumetric flask with deionized water. This methodcan be used to obtain a product which is mixture of a low molecularweight polymer and a monomer. A further dilution was performed to bringthe active material to a final concentration of 750 mg/L.

Method 4: The pyridine starting material (0.1 mol) was placed in a roundbottom flask. The reagent (R₁L) (0.105 mol) was added slowly, withstirring, to the starting material. After the reagent (R₁L) was added,the mixture was heated to 105-140° C. until the reaction wassubstantially complete. After reacting, the product was brought to afinal volume in a 100 mL volumetric flask with deionized water. Afurther dilution was performed to bring the active material to a finalconcentration of 750 mg/L.

Method 5: The pyridine starting material (0.1 mol) was dissolved inapproximately 25 mL of ethylene glycol in a round bottom flask. Thereagent (R₁L) (0.2 mol) was added slowly, with stirring, to the startingmaterial solution. After the alkylating agent was added, the mixture wasslowly heated to 105° C. and then brought to 130-140° C. The mixture washeated for several hours at 130-140° C. until the reaction wassubstantially complete. As much of the reagent (R₁L) as possible wasremoved by rotary evaporation. The product was brought to a final volumein a 100 mL volumetric flask with deionized water. A further dilutionwas performed to bring the active material to a final concentration of750 mg/L.

U.S. Pat. Nos. 4,212,764 and 5,824,756 also disclose polyvinylpyridinepolymerization.

Examples 2-17

The following pyridine starting materials and reagents (R₁L) werereacted following the methods above as indicated. The product activityin the Cu plating bath indicates the relative ability of the product toproduce an acceptable Cu deposit upon electrolytic deposition.

Ex- Pyridine Product am- Starting Synthetic Activity in ple MaterialReagent (R₁L) Method Cu bath 2 Poly(4-vinyl Me₂SO₄ Method 3 Very activepyridine) 3 Poly(4-vinyl methyl Method 3 Very active pyridine) tosylate4 4-vinyl Me₂SO₄ Method 1 and Very active; pyridine Method 3 exothermicat room temp 5 4-vinyl BzCl Method 1 Very active pyridine 6 4-vinylAllyl Method 1 Very active pyridine chloride 7 4-vinyl 2-chloroethanolMethod 5 Very active pyridine 8 4-vinyl Epichlorohydrin Method 2 Gelpyridine produced; exothermic after heating 9 4-vinyl 1- Method 1Insoluble in pyridine chloromethyl- H₂O naphthalene 10 4-vinyl 4- Method1 Relatively pyridine chloromethyl- less active pyridine 11 4-vinyl1,3-propane Method 1 Relatively pyridine sultone less active; exothermicabove room temper 12 4-vinyl methyl Method 2 and Very active; pyridinetosylate Method 3 exothermic after heating 13 4-vinyl chloroacetoneMethod 1 Very active pyridine 14 4-vinyl chloroacetonitrile Method 1Odor of HCN pyridine gas 15 4-vinyl 2-methoxy- Method 1 Very activepyridine ethoxymethyl chloride 16 4-vinyl 2-chloroethyl Method 4 Activepyridine ether 17 2-vinyl 2-chloroethanol Method 4 Active; pyridineincomplete reaction 18 2-vinyl methyl Method 2 and Relatively pyridinetosylate Method 3 less active 19 2-vinyl Me₂SO₄ Method 1 and Relativelypyridine Method 3 less active; exothermic at room temperature 20 4-vinyl1,3 dichloro Method 5 Very active pyridine propanol

In Examples 2 and 3, the poly(4-vinyl pyridine) starting material had amolecular weight of 16,000. In examples 4-20, the reaction products weremixtures of polymer and monomer to varying degrees, as the productsspontaneously polymerized after the quaternization reaction.

Example 21

Deposition from a Cu bath containing the reaction product ofpoly(4-vinyl pyridine) and dimethyl sulfate of Example 2

The following electroplating bath was prepared:

AMOUNT BASED INGREDIENT ON BATH Cu 40 grams per liter Sulfuric Acid 10grams per liter ViaForm ® suppressor 2 ml per liter ViaForm ®accelerator 9 ml per liter Reaction product of 4.5 mg per literpoly(4-vinyl pyridine and dimethyl sulfate) Chloride ion 50 mg/L

The bath was added to a 267 mL Hull cell. A brass Hull cellpanel/cathode was plated at 2 amperes for 3 minutes. The current densityvaried at different areas of the Hull Cell panel/cathode, from a low atsome areas of about 2 milliamperes per square cm to a high at otherareas of about 800 milliamperes per square cm. This plating bathproduced a Cu deposit which was very bright and uniform across theentire plating range.

Example 22

Deposition from a Cu bath containing the reaction product of 4-vinylpyridine and 2-chloroethanol of Example 7

The following electroplating bath was prepared:

AMOUNT BASED INGREDIENT ON BATH Cu 40 grams per liter Sulfuric Acid 10grams per liter ViaForm ® suppressor 2 ml per liter ViaForm ®accelerator 9 ml per liter Reaction product of 4-vinyl 3 mg per literpyridine and 2-chloroethanol Chloride ion 50 mg per liter

The bath was added to a 267 mL Hull cell. A brass Hull cellpanel/cathode was plated at 2 amperes for 3 minutes. The current densityvaried at different areas of the Hull Cell panel/cathode, from a low atsome areas of about 2 milliamperes per square cm to a high at otherareas of about 800 milliamperes per square cm. This plating bathproduced a Cu deposit which was very bright and uniform across theentire plating range.

Example 23

Deposition from a Cu bath containing the reaction product of 4-vinylpyridine and dimethyl sulfate of Example 4

The following electroplating bath was prepared:

AMOUNT BASED INGREDIENT ON BATH Cu 40 grams per liter Sulfuric Acid 10grams per liter ViaForm ® suppressor 2 ml per liter ViaForm ®accelerator 9 ml per liter Reaction product of 12 mg per liter 4-vinylpyridine and methyl sulfate Chloride ion 50 mg per liter

The bath was added to a 267 mL Hull cell. A brass Hull cellpanel/cathode was plated at 2 amperes for 3 minutes. The current densityvaried at different areas of the Hull Cell panel/cathode, from a low atsome areas of about 2 milliampere per square cm to a high at other areasof about 800 milliamperes per square cm. This plating bath produced a Cudeposit which was very bright and uniform across the entire platingrange.

Example 24

Four patterned test wafers (SiO₂ with Ta barrier available under thedesignation QCD from Sematech) characterized by 180 nm width trencheswere plated at 10 mA/cm² for 15 seconds each in solutions containing Cuions (40 g/L), sulfuric acid (10 g/L), chloride ions (50 mg/L), ViaForm®suppressor (2 ml/L), ViaForm® accelerator (9 ml/L), and varying levelercharacteristics.

FIG. 1 illustrates a cross section of a wafer plated with no leveler;FIG. 2 illustrates a cross section of a wafer plated with 10 ml/L of acommercially available leveler; FIG. 3 illustrates a cross section of awafer plated with 10 ml/L of a leveler constituting a polymer/monomermix prepared according to the protocol of Example 4; and FIG. 4illustrates a cross section of a wafer plated with 10 ml/L of a levelerconstituting a polymer prepared according to the protocol of Example 2.

FIG. 1 shows a great quantity of superfilling in 15 seconds with noleveler, demonstrated by the position and U-shape geometry of growthfront inside the feature. This indicates the bottom growth rate issignificantly greater than the sidewall growth. With the addition of 10ml/L of a commercially available leveler (FIG. 2), the growth frontposition is lower in the feature after 15 seconds, indicating sloweroverall fill commensurate with a significant degree of interference bythe leveler with superfilling. Also, the geometry of the growth front ismore V-shaped with the leveler, as contrasted with the generallyU-shaped profile in FIG. 1 with no leveler. The leveler, therefore,interferes with superfilling to some extent.

FIGS. 3 and 4 show an even greater quantity of fill in 15 seconds withtwo levelers of the invention of Examples 2 and 4. These levelers,therefore, do not substantially interfere with superfilling. These alsoshow that, advantageously, an essentially rectangular fill profile withangles of substantially 90° between the bottom of the fill and the sidewalls through the entire filling process. In contrast, the fills of FIG.2 (commercial leveler) show that a generally V-shaped fill profilebegins forming prior to the interconnects' being on the order of 75%full. The more rectangular fill profile of FIGS. 3 and 4 is moreadvantageous because there is less risk of voiding and pinching off thanwith V-shaped fill profiles.

Example 25

Three test wafers (200 mm diameter; designation QCD from Sematech)characterized by 180 nm width trenches were plated each in a SabreCopper Plating Tool available from Novellus in solutions containing Cuions (40 g/L), sulfuric acid (10 g/L), chloride ions (50 mg/L), ViaForm®suppressor (2 ml/L), ViaForm® accelerator (9 ml/L), and no leveler.

FIGS. 5 and 6 illustrate a cross section of a center (FIG. 5) and anedge (FIG. 6) of a wafer plated at a wafer rotation speed of 30 rpm, anda current of 3 A for 33 seconds followed by 18 A for 25 seconds. FIGS. 7and 8 illustrate a cross section of a center (FIG. 7) and an edge (FIG.8) of a wafer plated under these conditions at a wafer rotation speed of125 rpm, and a current of 3 A for 33 seconds followed by 18 A for 25seconds. FIGS. 9 and 10 illustrate a cross section of a center (FIG. 9)and an edge (FIG. 10) of a wafer plated under these conditions at awafer rotation speed of 30 rpm, and a current of 1.5 A for 27 secondsfollowed by 3 A for 27 seconds followed by 12 A for 44 seconds.

Example 26

Three test wafers (200 mm diameter; designation QCD from Sematech)characterized by 180 nm width trenches were plated each in solutionscontaining Cu ions (40 g/L), sulfuric acid (10 g/L), chloride ions (50mg/L), ViaForm® suppressor (2 ml/L), ViaForm® accelerator (9 ml/L), and6 ml/L of a leveler constituting a polymer/monomer mix preparedaccording to the protocol of Example 4.

FIGS. 11 and 12 illustrate a cross section of a center (FIG. 11) and anedge (FIG. 12) of a wafer plated at a wafer rotation speed of 30 rpm,and a current of 3 A for 33 seconds followed by 18 A for 25 seconds.FIGS. 13 and 14 illustrate a cross section of a center (FIG. 13) and anedge (FIG. 14) of a wafer plated under these conditions at a waferrotation speed of 125 rpm, and a current of 3 A for 33 seconds followedby 18 A for 25 seconds. FIGS. 15 and 16 illustrate a cross section of acenter (FIG. 15) and an edge (FIG. 16) of a wafer plated under theseconditions at a wafer rotation speed of 30 rpm, and a current of 1.5 Afor 27 seconds followed by 3 A for 27 seconds followed by 12 A for 44seconds.

Example 27

Three test wafers (200 mm diameter; designation QCD from Sematech)characterized by 180 nm width trenches were plated each in solutionscontaining Cu ions (40 g/L), sulfuric acid (10 g/L), chloride ions (50mg/L), ViaForm® suppressor (2 ml/L), ViaForm® accelerator (9 ml/L), and6 ml/L of a leveler constituting a polymer prepared according to theprotocol of Example 2.

FIGS. 17 and 18 illustrate a cross section of a center (FIG. 17) and anedge (FIG. 18) of a wafer plated at a wafer rotation speed of 30 rpm,and a current of 3 A for 33 seconds followed by 18 A for 25 seconds.FIGS. 19 and 20 illustrate a cross section of a center (FIG. 19) and anedge (FIG. 20) of a wafer plated under these conditions at a waferrotation speed of 125 rpm, and a current of 3 A for 33 seconds followedby 18 A for 25 seconds. FIGS. 21 and 22 illustrate a cross section of acenter (FIG. 21) and an edge (FIG. 22) of a wafer plated under theseconditions at a wafer rotation speed of 30 rpm, and a current of 1.5 Afor 27 seconds followed by 3 A for 27 seconds followed by 12 A for 44seconds.

Comparing the deposits of FIGS. 5-10 (no leveler) to those of FIGS.11-16 (leveler of Ex. 4) and 17-22 (leveler of Ex. 2), the superiorleveling characteristics of the invention are demonstrated, asoverplating and mounding are substantially reduced. Without the levelingcomponent, a significantly greater thickness of Cu must be deposited toachieve a sufficiently planar surface for subsequent CMP operations,which substantially increases the costs associated with both Cu platingand CMP processes.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. Forexample, that the foregoing description and following claims refer to“an” interconnect means that there are one or more such interconnects.The terms “comprising”, “including” and “having” are intended to beinclusive and mean that there may be additional elements other than thelisted elements.

As various changes could be made in the above without departing from thescope of the invention, it is intended that all matter contained in theabove description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense. The scope ofinvention is defined by the appended claims and modifications to theembodiments above may be made that do not depart from the scope of theinvention.

DEFINITIONS

Unless otherwise indicated, the alkyl groups described herein arepreferably lower alkyl containing from one to eight carbon atoms in theprincipal chain and up to 20 carbon atoms. They may be straight orbranched chain or cyclic and include methyl, ethyl, propyl, isopropyl,butyl, hexyl, and the like.

Unless otherwise indicated, the alkenyl groups described herein arepreferably lower alkenyl containing from two to eight carbon atoms inthe principal chain and up to 20 carbon atoms. They may be straight orbranched chain or cyclic and include ethenyl, propenyl, isopropenyl,butenyl, isobutenyl, hexenyl, and the like.

Unless otherwise indicated, the “substituted alkyl, or substitutedalkenyl” moieties described herein are alkyl or alkenyl moieties whichare substituted with at least one atom other than carbon, includingmoieties in which a carbon chain atom is substituted with a hetero atomsuch as nitrogen, oxygen, silicon, phosphorous, boron, sulfur, or ahalogen atom. These substituents include halogen, heterocyclo, alkoxy,alkenoxy, alkynoxy, aryloxy, hydroxy, protected hydroxy, keto, acyl,acyloxy, nitro, amino, amido, cyano, thiol, ketals, acetals, esters, andethers.

The terms “aryl” or “ar” as used herein alone or as part of anothergroup denote optionally substituted homocyclic aromatic groups,preferably monocyclic or bicyclic groups containing from 6 to 12 carbonsin the ring portion, such as phenyl, biphenyl, naphthyl, substitutedphenyl, substituted biphenyl or substituted naphthyl. Phenyl andsubstituted phenyl are the more preferred aryl.

The term “aralkyl” as used herein alone or as part of another groupdenotes optionally substituted homocyclic aromatic groups wherein acarbon of the aromatic group is attached directly to a carbon of analkyl group and the aralkyl moiety is attached to the derivative throughthe alkyl group. The aromatic groups and alkyl groups comprising thearalkyl group are defined above.

The terms “halogen” or “halo” as used herein alone or as part of anothergroup refer to chlorine, bromine, fluorine, and iodine.

Unless otherwise indicated, the term “heteroarylalkyl” designates aheteroaryl group as defined herein attached to an alkyl group as definedherein which acts as a linker group to the rest of the molecule.

The term “heteroaryl” as used herein alone or as part of another groupdenote optionally substituted aromatic groups having at least oneheteroatom in at least one ring, and preferably 5 or 6 atoms in eachring. The heteroaromatic group preferably has 1 or 2 oxygen atoms, 1 or2 sulfur atoms, and/or 1 to 4 nitrogen atoms in the ring, and may bebonded to the remainder of the molecule through a carbon or heteroatom.Exemplary heteroaromatics include furyl, thienyl, pyridyl, oxazolyl,pyrrolyl, indolyl, quinolinyl, or isoquinolinyl and the like. Exemplarysubstituents include one or more of the following groups: hydrocarbyl,substituted hydrocarbyl, keto, hydroxy, protected hydroxy, acyl,acyloxy, alkoxy, alkenoxy, alkynoxy, aryloxy, halogen, amido, amino,nitro, cyano, thiol, ketals, acetals, esters, and ethers.

The term “acyl” as used herein alone or as part of another group,denotes the moiety formed by removal of the hydroxyl group from thegroup —COOH of an organic carboxylic acid, e.g., RC(O)—, wherein R isR¹, R¹O—, R¹R²N—, or R¹S—, R¹ is hydrocarbyl, heterosubstitutedhydrocarbyl, or heterocyclo and R² is hydrogen, hydrocarbyl, orsubstituted hydrocarbyl.

The term “acyloxy,” as used herein alone or as part of another group,denotes an acyl group as described above bonded through an oxygenlinkage (—O—), e.g., RC(O)O— wherein R is as defined in connection withthe term “acyl.”

1. A method for electroplating Cu onto a substrate having electricalinterconnect features in the manufacture of a microelectronic device,the method comprising: immersing the substrate in an electrolyticsolution comprising the following: a source of Cu ions in an amountsufficient to electrodeposit Cu onto the substrate and into theelectrical interconnect features wherein the electrical interconnectfeatures comprise openings of less than about 100 nm and the electricalinterconnect features have an aspect ratio (depth:width) of greater thanabout 4:1; one or more superfilling agent compounds which promote a Cudeposit in the interconnect features characterized by a rate of growthin the vertical direction which is substantially greater than a rate ofgrowth in the horizontal direction, wherein the superfilling agentcompounds are selected from the group consisting of an accelerator, asuppressor, and combinations thereof; and a leveling agent comprising asubstituted pyridyl polymer compound which has a leveling effect withoutsubstantially interfering with superfilling, wherein the substitutedpyridyl polymer compound is a reaction product obtained by causing (i) apyridine starting material selected from the group consisting of 4-vinylpyridine and poly(4-vinylpyridine) to react with (ii) a reagent selectedfrom the group consisting of dimethyl sulfate and methyl tosylate; andsupplying electrical current to the electrolytic solution to deposit Cuonto the substrate.
 2. The method of claim 1 wherein the substrate is asemiconductor integrated circuit device substrate with said electricalinterconnect features.
 3. The method of claim 1 wherein the substitutedpyridyl polymer compound is a reaction product of 4-vinyl pyridine anddimethyl sulfate.
 4. The method of claim 1 wherein the substitutedpyridyl polymer compound has a molecular weight between about 10,000 and20,000 g/mol.
 5. The method of claim 1 wherein the substituted pyridylpolymer compound has a molecular weight between about 60,000 and 160,000g/mol.
 6. The method of claim 1 wherein the electrolytic solutionconsists essentially of: the source of Cu ions in an amount sufficientto electrodeposit Cu onto the substrate and into the electricalinterconnect features wherein the electrical interconnect featurescomprise openings of less than about 100 nm and the electricalinterconnect features have an aspect ratio (depth:width) of greater thanabout 4:1; the one or more superfilling agent compounds which promote aCu deposit in the interconnect features characterized by a rate ofgrowth in the vertical direction which is substantially greater than arate of growth in the horizontal direction, wherein the superfillingagent compounds are selected from the group consisting of anaccelerator, a suppressor, and combinations thereof; and the levelingagent comprising a substituted pyridyl polymer compound which has aleveling effect without substantially interfering with superfilling,wherein the substituted pyridyl polymer compound is a reaction productobtained by causing (i) a pyridine starting material selected from thegroup consisting of 4-vinyl pyridine and poly(4-vinylpyridine) to reactwith (ii) a reagent selected from the group consisting of dimethylsulfate and methyl tosylate.
 7. The method of claim 1 wherein theleveling agent consists of the substituted pyridyl polymer compoundwhich has a leveling effect without substantially interfering withsuperfilling, wherein the substituted pyridyl polymer compound is areaction product obtained by causing (i) a pyridine starting materialselected from the group consisting of 4-vinyl pyridine andpoly(4-vinylpyridine) to react with (ii) a reagent selected from thegroup consisting of dimethyl sulfate and methyl tosylate.
 8. The methodof claim 1 wherein the substituted pyridyl polymer compound is areaction product of poly(4-vinylpyridine) and methyl tosylate.
 9. Themethod of claim 1 wherein the substituted pyridyl polymer compound is areaction product of 4-vinyl pyridine and methyl tosylate.